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import theano
import numpy
from theano import tensor
from blocks.model import Model
from blocks.bricks import Linear, Tanh
from ctc_cost import CTC
from blocks.initialization import IsotropicGaussian, Constant
from fuel.datasets import IterableDataset
from fuel.streams import DataStream
from blocks.algorithms import (GradientDescent, Scale,
StepClipping, CompositeRule)
from blocks.extensions.monitoring import TrainingDataMonitoring
from blocks.main_loop import MainLoop
from blocks.extensions import FinishAfter, Printing
from blocks.bricks.recurrent import SimpleRecurrent
from blocks.graph import ComputationGraph
try:
import cPickle as pickle
except:
import pickle
floatX = theano.config.floatX
@theano.compile.ops.as_op(itypes=[tensor.lvector],
otypes=[tensor.lvector])
def print_pred(y_hat):
blank_symbol = 4
res = []
for i, s in enumerate(y_hat):
if (s != blank_symbol) and (i == 0 or s != y_hat[i - 1]):
res += [s]
return numpy.asarray(res)
n_epochs = 200
x_dim = 4
h_dim = 9
num_classes = 4
with open("ctc_test_data.pkl", "rb") as pkl_file:
try:
data = pickle.load(pkl_file)
inputs = data['inputs']
labels = data['labels']
# from S x T x B x D to S x T x B
inputs_mask = numpy.max(data['mask_inputs'], axis=-1)
labels_mask = data['mask_labels']
except:
data = pickle.load(pkl_file, encoding='bytes')
inputs = data[b'inputs']
labels = data[b'labels']
# from S x T x B x D to S x T x B
inputs_mask = numpy.max(data[b'mask_inputs'], axis=-1)
labels_mask = data[b'mask_labels']
print('Building model ...')
# T x B x F
x = tensor.tensor3('x', dtype=floatX)
# T x B
x_mask = tensor.matrix('x_mask', dtype=floatX)
# L x B
y = tensor.matrix('y', dtype=floatX)
# L x B
y_mask = tensor.matrix('y_mask', dtype=floatX)
x_to_h = Linear(name='x_to_h',
input_dim=x_dim,
output_dim=h_dim)
x_transform = x_to_h.apply(x)
rnn = SimpleRecurrent(activation=Tanh(),
dim=h_dim, name="rnn")
h = rnn.apply(x_transform)
h_to_o = Linear(name='h_to_o',
input_dim=h_dim,
output_dim=num_classes + 1)
h_transform = h_to_o.apply(h)
# T x B x C+1
y_hat = tensor.nnet.softmax(
h_transform.reshape((-1, num_classes + 1))
).reshape((h.shape[0], h.shape[1], -1))
y_hat.name = 'y_hat'
y_hat_mask = x_mask
cost = CTC().apply(y, y_hat, y_mask, y_hat_mask, 'normal_scale')
cost.name = 'CTC'
# Initialization
for brick in (rnn, x_to_h, h_to_o):
brick.weights_init = IsotropicGaussian(0.01)
brick.biases_init = Constant(0)
brick.initialize()
print('Bulding DataStream ...')
dataset = IterableDataset({'x': inputs,
'x_mask': inputs_mask,
'y': labels,
'y_mask': labels_mask})
stream = DataStream(dataset)
print('Bulding training process...')
algorithm = GradientDescent(cost=cost,
parameters=ComputationGraph(cost).parameters,
step_rule=CompositeRule([StepClipping(10.0),
Scale(0.02)]))
monitor_cost = TrainingDataMonitoring([cost],
prefix="train",
after_epoch=True)
# sample number to monitor
sample = 8
y_hat_max_path = print_pred(tensor.argmax(y_hat[:, sample, :], axis=1))
y_hat_max_path.name = 'Viterbi'
monitor_output = TrainingDataMonitoring([y_hat_max_path],
prefix="y_hat",
every_n_epochs=1)
length = tensor.sum(y_mask[:, sample]).astype('int32')
tar = y[:length, sample].astype('int32')
tar.name = '_Target_Seq'
monitor_target = TrainingDataMonitoring([tar],
prefix="y",
every_n_epochs=1)
model = Model(cost)
main_loop = MainLoop(data_stream=stream, algorithm=algorithm,
extensions=[monitor_cost, monitor_output,
monitor_target,
FinishAfter(after_n_epochs=n_epochs),
Printing()],
model=model)
print('Starting training ...')
main_loop.run()
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